JP4790196B2 - System and method for real time correction of light output and / or color - Google Patents

Abstract

The present invention relates to a system and method for real time correction of light output and/or colour of an image displayed on a display device. The system comprises: a display device (1) comprising an active display area (6) for displaying the image, an image forming device (2) and an electronic driving system (4) for driving the image forming device (2), an optical sensor unit (10) comprising an optical aperture (21) and a light sensor (22) having an optical axis, to make optical measurements on a light output from a representative part of the active display area (6) of the image forming device (2) and generating optical measurement signals (11) therefrom, a feedback system (12) receiving the optical measurement signals (11) and on the basis thereof controlling the electronic driving system (4). The optical aperture (21) of the optical sensor unit (10) has an acceptance angle such that at least 50%, alternatively 60%, alternatively 70%, alternatively 75% of the light received by the sensor (22) comes from light travelling within 15 DEG of the optical axis of the light sensor (22). <IMAGE>

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
This invention is on a kind of display device having a display area whose luminance vs. voltage characteristics depend on the temperature and aging of the display device, such as LCD (liquid crystal display) devices, plasma equipment, CRTs, electronic displays, rear projection systems, etc. The present invention relates to a system and method for real time correction of light output and / or color of displayed images.
[0002]
The present invention relates to, but is not limited to, a transmissive liquid crystal display intended to be viewed along a given visual axis. This is especially true for computer screens and instrument panels of vehicles such as aircraft.
[0003]
More specifically, it is desirable that the appearance of each of the LCD screens be the same, for example when a plurality of LCD screens are brought together to form one or more images.
[0004]
BACKGROUND OF THE INVENTION
Currently, LCD displays are often provided with contrast adjustment means, and contrast adjustment is performed at the beginning of the use phase of the display. The contrast is no longer adjusted while the display is in use.
[0005]
JP-8292129 describes a separate measuring device that is placed on the display only when a measurement is performed. Such a sensor for measuring the light of the display has any one of an optical system, an aperture, and an optical fiber mounted on the display surface. Of all the light beams emitted from the display surface, only the light corresponding to the optimum viewing angle is provided in the sensor element. The described sensor does not consider compactness and integration. The height of the sensor is large, because in order to give the sensor element only light corresponding to the optimum observation angle, the sensor element has to be placed at a considerable distance from the aperture and thus from the screen. . The sensor also covers a fairly large area. The described sensors are not designed for real-time use in parallel with the applications displayed on the screen. This would be impractical for mobile phone displays, for example.
[0006]
For some applications, it is preferred that the measuring instrument is always on the display and can constantly measure the light output and thus constantly correct the light output and / or color of the displayed image.
[0007]
From EP-0313331, an apparatus for controlling the brightness and contrast during actual use of a liquid crystal display is known. A predetermined level of light is generated by the light emitting diode and transmitted through the LCD panel. On the opposite side of the panel, the light transmitted through the panel is sensed by the sensor and a signal representative thereof is generated correspondingly. This signal is monitored in real time and used to adjust the gray scale level of the panel in real time. The light emitting diodes and sensors are positioned on opposite surfaces of the LCD panel, below the light blocking material. This shading material blocks the light generated in that part of the screen for the viewer and the ambient light for the sensor. The disadvantage of this solution is that it cannot be retrofitted to an existing screen. Furthermore, such a covered test pixel does not have any problems with ambient light, but it covers the LCD too much.
[0008]
US Pat. No. 5,162,785 and DE-4129646 also describe devices for optimizing the contrast of LCDs. The LCD panel includes a display area and a separate test zone. The sensor observes the test zone. Both the sensor and the test zone are protected against ambient light by an optical mask.
[0009]
US-5490005 describes a light sensor placed on its own light source (LED) of the display device. The first disadvantage is that this cannot be realized on a commercially available LCD panel. A further disadvantage is that the feedback loop does not incorporate the backlight used for the active image content and therefore the structure is not very precise. That is, it does not measure the overall result of all the elements that define the image (LCD itself, backlight, filter, temperature, etc.).
[0010]
SUMMARY OF THE INVENTION
The object of the present invention is to overcome the above disadvantages.
[0011]
This object is achieved by the method and system according to the invention.
The present invention provides a system for real-time correction of the light output and / or color of an image displayed on a display device by optical feedback. The light output includes backlight, contrast and / or brightness. The system according to the invention includes:
An active display area for displaying the image and an electronic drive for driving the image forming device and the image forming device, for example a transmissive or reflective LCD in the case of an LCD device or a phosphor in the case of a CRT; A display device, including a system,
An optical aperture comprising an optical aperture and an optical sensor having an optical axis for making an optical measurement of light output from a part representative of the active display area of the imaging device and generating an optical measurement signal therefrom; Sensor unit,
A feedback system that receives the optical measurement signal and controls the electronic drive system based thereon; The optical aperture of the optical sensor has a light receiving angle (ie, the sensor light receiving angle is 30 °) such that at least 50% of the light received by the sensor comes from light traveling within 15 ° from the optical axis of the optical sensor. In other words, the acceptance angle of the sensor is the amount of control light emitted or reflected from the display area with a relative acceptance angle of 30 ° or less and the emission angle from the display area with a relative acceptance angle greater than 30 °. Or an angle such that the ratio between the amount of control light reflected is X: 1, where X is 1 or greater. Depending on the situation, there may be an acceptance angle such that at least 60% of the light received by the photosensor, or alternatively at least 70%, or at least 75% comes from light traveling within 15 ° from the optical axis of the photosensor. Would be advantageous.
[0012]
In another aspect of the invention, a system for real time correction of light output and / or color of an image displayed on a display device is provided, including:
An active display area for displaying the image and an electronic drive for driving the image forming device and the image forming device, for example a transmissive or reflective LCD in the case of an LCD device or a phosphor in the case of a CRT; A display device, including a system,
An optical aperture comprising an optical aperture and an optical sensor having an optical axis for making an optical measurement of light output from a part representative of the active display area of the imaging device and generating an optical measurement signal therefrom; Sensor unit,
A feedback system that receives the optical measurement signal and controls the electronic drive system based thereon;
The optical aperture of the optical sensor unit is at least 25% attenuated for light received by the sensor when the angle with the optical axis of the optical sensor is 10 ° or greater, and at least 55% attenuated for light received at an angle greater than 20 °. And has a light receiving angle such that light arriving at an angle of 35 ° or more is attenuated by at least 85%.
[0013]
The system according to the invention is intended to be used in real time and thus during the display of the main application. A test pattern is not required, but a test pattern may be used. The main application is unimpeded when the measurement is made.
[0014]
The optical measurement is not differential, i.e. it does not measure the ambient light and the actual light emitted by the active display area separately. Direct ambient light is not measured and this does not appreciably affect the measurement. Indirect ambient light (ie ambient light reflected by the display) contributes to the total luminance output of the electronic display and will therefore be measured.
[0015]
The invention can be combined with a separate ambient light sensor if it is intended to adjust the brightness of the display with respect to ambient light. In this case, the system according to the invention measures the brightness emitted by the screen and the ambient light sensor measures the ambient light. The display brightness can then be adjusted in proportion to the difference between the two.
[0016]
Preferably, the optical measurement is a luminance measurement. In this case, the light output correction may include brightness and / or contrast correction. The optical measurement may also be a color measurement, in which case color correction can be performed.
[0017]
The feedback system preferably includes an optical measurement signal, a comparator / amplifier that compares the measured brightness or color value with a reference value, backlight control and / or video contrast control and / or video brightness control and / or color temperature. An adjuster for adjusting, thus reducing the difference between the reference value and the measured value so that this difference is as close to zero as possible.
[0018]
The optical sensor unit of the present invention preferably includes a light guide between the optical aperture and the optical sensor. This light guide may be, for example, a light pipe or an optical fiber.
[0019]
Preferably, the portion representative of the active display area of the image forming apparatus is less than 1%, preferably less than 0.1%, and even more preferably less than 0.01% of the total area of the active display area of the image forming apparatus. .
[0020]
According to a preferred embodiment, the optical aperture of the optical sensor unit masks a part of the active display area, while the photosensor itself does not mask any part of the active display area. The light output from the front of the active display area of the display device is continuously measured while minimizing the coverage of the observed image. The light sensor may be placed behind or on the side of the display area, so that the required height above the screen area is preferably less than 5 mm. Thus, the distance between the optical aperture and the light sensor that is required to reject ambient light during the measurement is not caused by the distance outside the screen.
[0021]
The area measured on the screen consists of a number of active pixels in the active display area. The area of active pixels measured on the screen is preferably at most 6 mm × 4 mm. For example, in a mobile phone (third generation mobile phone) screen with typical dimensions of the active display area of 50 mm × 80 mm, a 6 mm × 4 mm measurement zone constitutes 0.6% of the active display area. The active display area dimensions are 245.9 mm x 184.4 For a mm laptop screen (12.1 inch screen), a 6 mm × 4 mm measurement zone constitutes 0.0005% of its active display area.
[0022]
Dedicated test pixels are not required, and any pixel in the active display area can be used to make optical measurements. A test patch may be generated and superimposed on the active pixels observed by the sensor, or the sensor may observe a portion of the actual active image. This allows the system to be retrofitted onto any existing display device. This can be combined with a standard display such as an AM-LCD (active matrix liquid crystal display) without the need for a dedicated light source or backlight. Furthermore, parts of the display device such as a screen can be easily replaced.
[0023]
Preferably, the optical sensor unit housing protrudes above the active display area by a distance of less than 0.5 cm.
[0024]
The present invention also provides a method for real time correction of the light output and / or color of an image displayed on a display device by optical feedback. The method includes the following steps.
-Displaying an image on an active display area on the display device;
Performing optical measurements on light emitted from a portion representative of the active display area and generating optical measurement signals therefrom;
-Controlling the display of the image on the active display area according to the optical measurement signal. The steps of making an optical measurement include the amount of control light emitted or reflected from the display area with a relative acceptance angle of 30 ° or less and the control light emitted or reflected from the display area with a relative acceptance angle greater than 30 °. Selecting light such that the ratio to the amount of light is X: 1, where X is 1 or greater.
[0025]
The method according to the invention is:
-Displaying an image on an active display area on the display device;
Performing optical measurements on light emitted from a portion representative of the active display area and generating optical measurement signals therefrom;
-Controlling the display of the image on the active display area according to the optical measurement signal,
The optical measuring step comprises attenuating at least 25% light traveling at an angle with respect to the normal to the active display area of at least 25% and at least light traveling at an angle with respect to the active display area of at least 20 °; Selecting light to be used in the control step by attenuating 55% and attenuating at least 85% the light traveling at an angle of 35 ° or more with the normal to the active display area.
[0026]
By the method of the invention, a controlled light output and / or correct absolute luminance and color (Y, x, y) reading can be obtained from the display device.
[0027]
The method of correcting the image is used in real time, ie in parallel with the application being performed. This method is intervention-free and does not require input from the user.
[0028]
Preferably, the optical measurement performed is a luminance measurement. In this case, the light output correction may include brightness and / or contrast correction. Alternatively, the optical measurement performed is a color measurement, in which case the light output correction includes a color correction of the displayed image.
[0029]
Control of the display of the image according to the optical measurement signal preferably compares the measurement signal with a reference value and adjusts the backlight controller and / or video contrast control and / or video brightness control and / or color temperature, and thus the reference value This is done by reducing the difference between the signal and the measurement signal and bringing this difference as close to zero as possible.
[0030]
Preferably, the step of performing the optical measurement further includes transmitting light emitted from the active display area from the inside of the active display area to the outside of the active display area.
[0031]
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
[0032]
In the different drawings, the same reference signs refer to the same or analogous elements.
[0033]
[Description of Example]
The invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the following, the acceptance angle of the sensor refers to the angle to which extreme light rays that can enter the sensor are opposed. Therefore, normally, the angle between the optical axis and the light beam at the end point is half of the light receiving angle.
[0034]
1A and 1B are a plan view and a front view, respectively, of a part of an LCD display device 1 having an embodiment of an optical sensor unit 10 according to the present invention.
[0035]
The LCD display device 1 includes an LCD panel 2 and an electronic drive system 4 for driving the LCD panel 2 to generate and display an image. The display device 1 has an active display area 6 on which an image is displayed. The LCD panel 2 is fixed to the LCD panel bezel 8.
[0036]
According to the present invention, the display device 1 includes an optical sensor unit 10 and performs optical measurement of light output from a portion representing the LCD panel 2. An optical measurement signal 11 is generated from these optical measurements.
[0037]
The feedback system 12 receives the optical measurement signal 11 and controls the electronic drive system 4 based on these signals.
[0038]
There are several ways to realize the optical sensor unit 10. In any case, the optical sensor unit 10 is fixed to (or adjacent to) the active display area 6 either permanently or detachably. The entire optical sensor unit 10 can be calibrated and can also be interchangeable.
[0039]
The optical sensor unit 10 typically has a light incident surface or optical aperture 21 and a light emitting surface 23. Furthermore, it also has an internal reflection surface. The light incident surface 21 is preferably in static contact with the active display area 6 that is shielded from ambient light. If the contact is not light blocking, it may be necessary to use an additional ambient light sensor that is used to compensate for ambient light level to compensate for ambient light.
[0040]
Preferably, the optical sensor unit 10 protrudes above the active display area by a distance D of 5 mm or less.
[0041]
As shown in FIG. 2, according to the first embodiment, the optical sensor unit 10 includes an optical aperture 21, a photodiode sensor 22, and a light guide 34 between them, for example, bulk PMMA (polymethyl methacrylate). ) Structures 14, 16, 18, 20, one of which provides a condensing aperture 21 and one of which provides a light exit surface 23. PMMA is a transparent (over 90% transmission) hard and strong material. One skilled in the art will recognize that other materials such as glass may be used.
[0042]
The massive PMMA structures 14, 16, 18, 20 serve to guide the rays using total reflection. PMMA structures 14 and 18 deflect light beams exceeding 90 °. The approximate path of the two rays 24, 26 is shown in FIG.
[0043]
The inclined portions of PMMA structures 14 and 18 are preferably metallized 28, 30 to serve as mirrors. Other surfaces need not be metallized because light travels through the PMMA structure using total internal reflection.
[0044]
There is an air gap between the different PMMA structures 14, 16, 18 and 20. At these interfaces, stray light (not light emitted by the display device) can enter the light guide 34.
[0045]
This first embodiment has the disadvantage of being quite complex to implement. Further, stray light and ambient light can enter the light guide 34, thereby reducing the signal-to-noise ratio of the measured light output.
[0046]
A second embodiment of the optical sensor unit 10 according to the present invention is shown in FIG. This is an implementation example using an optical fiber. The optical sensor unit 10 includes an optical aperture 21, an optical sensor 22, and an optical fiber bundle 32 therebetween. The optical fibers are preferably fixed or bundled together (eg glued) and the end faces are polished so that only light rays under a limited angle (as defined in the appended claims) are accepted. To do.
[0047]
This embodiment presents the disadvantage that bending an optical fiber bundle with a small radius is often impractical. Therefore, the distance D that the optical sensor unit 10 extends from the display area 6 of the display device 1 is considerably large. In addition, there may be light leakage, especially on surfaces where the optical fiber bends more than 90 °. Ambient light can enter the light guide 34, but this can be easily limited by applying a light shielding material directly or indirectly to the surface of the fiber bundle. “Directly” means that the shielding material and the fiber bundle cannot be separated, for example, a damped metal on the fiber bundle. “Indirectly” means that the shielding material and the fiber bundle are separable, such as a detachable flexible pipe with an inner damping metal placed around the fiber bundle.
[0048]
A third and preferred embodiment of the optical sensor unit according to the invention is shown in FIGS. In this embodiment, the optical sensor unit 10 includes a light guide 34 made of a piece of PMMA. The optical sensor unit 10 further includes an opening 21 at one end of the light guide 34 and a photodiode sensor 22 or equivalent device at the other end of the light guide 34. The light guide 34 may have a non-uniform cross section so as to concentrate the light on the light exit surface 23.
[0049]
The light beam travels through the light guide 34 by total internal reflection. The light rays are deflected by the reflection regions 28, 30 at an angle of 90 °, which are metalized, for example, as in the first embodiment, to act as mirrors. The structure of the light guide 34 is rigid and easy to manufacture.
[0050]
In one refinement of the structure (see FIG. 5), the reflective coating 36 is direct or indirect (ie non-separable) except for the area where light is coupled in (opening 21) or exiting (light exit surface 23). (Or separable) applied to the outer surface of the light guide 34. The reflection coating material 36 has a reflection coefficient of 0.9 or less. The coating is on the surface of the light guide 34 and cannot penetrate into it.
[0051]
In this case, ambient light can be rejected very well. At the same time, the light receiving angle is narrow in this structure. That is, rays that enter the light guide 34 under a wide angle with respect to the normal to the active display region 6, such as the rays indicated by the dashed line 38, enter the structure under a narrow angle with respect to the normal to the active display region 6. Rather, it will be reflected and attenuated much more (because the reflection coefficient is 0.9 or less).
[0052]
As shown in FIG. 6, this structure can be further modified to change the light receiving angle. By selectively omitting the reflective layer 36 on the surface of the light guide 34 where the structure is not exposed to ambient light (eg, covered by the display housing 42), the axis of the light guide 34 (or a method for the active display area 6). Rays traveling under a large angle with respect to the line) can be emitted from the optical sensor unit 10 while ambient light does not enter the light guide 34.
[0053]
Thus, light rays that enter the light guide 34 under a wide angle with respect to the normal to the active display area 6, such as the light rays shown by the dashed line 38, can be further attenuated and even exit the light guide 34. Light rays that enter the light guide 34 under a small angle with respect to the normal of the active display area 6, such as the light shown by the dotted line 40, are less attenuated and light guide only at the level of the light exit surface 23 and the photodiode sensor 22. 34 will leave. Thus, the light guide 34 is much more selective as a function of the incident angle of the light beam. This means that the light guide 34 realizes a narrow light receiving angle.
[0054]
Due to the small acceptance angle of the optical sensor unit 10 according to the invention, ambient light is prevented from entering the photodiode sensor 22 and there is no need to shield pixels adjacent to the pixel to be measured from ambient light. . Also, light emitted by the LCD screen at a shallow angle with respect to its surface also does not enter the sensor. Light emitted from an LCD display at an angle away from the normal to the surface is often distorted in brightness and color.
[0055]
In order to measure the light receiving angle characteristics of the optical sensor unit 10, the test conditions and apparatus described below were used. A light source 44 having a white uniform light output, such as a Hoffman light source type LS-65-GF / PS, is placed in a dark room 46. The light guide 34 according to the present invention is placed so that the opening 21 comes in front of the light guide 34, and in the first example, the light enters the opening 21 in a direction perpendicular to the opening 21. One preferred requirement of the measurement mechanism is that the distance d between the light source 44 and the opening 21 of the light guide 34 is equal to or greater than 50 times the width c of the opening surface of the light guide 34. This is to limit the angular spread of light entering the light guide. For example, the width c of the opening 21 may be 3 mm, and the distance between the light source 44 and the opening 21 of the light guide 34 may be 17 cm. Thus, for practical purposes, most incoming light rays are orthogonal to the entrance of the optical sensor unit 10. Light exiting the light guide 34 at the light exit surface 23 is captured by the photodiode 22, and the measured light is converted to a voltage by a light-voltage conversion circuit 47 (linear circuit), which is, for example, Philips It is measured by a digital voltmeter 48 such as PM2525 type. A flat table is provided, a part of which can be rotated in the plane of the table about a vertical axis. In order to measure the rotation of the rotatable part of the table, for example, a protractor (not shown) supplied by Helios is provided.
[0056]
The light guide 34 is fixed to a rotatable portion of the table so that the light guide 34 can rotate on a plane parallel to a line connecting the light source 44 and the opening 21 of the light guide 34. After alignment, the light source 44 is fixed to a non-rotatable part of the table. Alternatively, the light guide 34 may be fixed to a fixed portion of the table, and the light source 44 may be fixed to a rotatable portion of the table.
[0057]
A measured value of 0 ° means that the light entering the light guide 34 travels parallel to the optical axis of the light source 44. In this position, the optical input of the optical system is maximum. A measured value of 90 ° means that the light entering the light guide 34 is orthogonal to the optical axis of the light source 44. In this position, the optical input of the optical system is minimal. Note that since the light receiving angle is the relative angle of the light beam at the end point, the measured value of angle a ° indicates the light receiving angle of 2a °.
[0058]
A suitable method of measurement is as follows. The rotating part of the turntable is rotated by 1 ° (for point e, see FIG. 8) until it reaches 15 °. A protractor is used for this. The 5 ° step is then applied until 50 ° is reached. Finally, apply the 10 ° step to 90 °. In either step, the corresponding measured voltage is recorded.
[0059]
Since the angle is two-dimensional, the entrance position of the optical system preferably rotates also in the orthogonal direction (see FIG. 9). The amount of steps used depends on the symmetry of the optical sensor unit 10.
[0060]
Since the light guide 34 is typically symmetric, the resulting graphs (FIGS. 10A and 10B) can be mirror images at 0 °. All measurements must be performed in a dark room to eliminate the external effects of light. The ambient temperature is typically chosen to be reasonable for LCD operation, such as 25 °.
[0061]
FIGS. 10A and 10B show measurement results related to characteristics determined by horizontal rotation and vertical rotation, respectively. Convert the measured bolt value to a percentage value by linear interpolation. The graph shows narrow characteristics.
[0062]
Looking at the horizontal characteristics, the angle is about 15 ° when V% drops to 50% of the light received at 0 °. For rays arriving at 35 °, only about 10% of the light is received.
[0063]
The graph for vertical characteristics does not show a substantial difference from the graph for horizontal characteristics.
[0064]
As shown in the graph, the light receiving angle of the light guide according to the present invention is such that light arriving at an angle of 10 ° or more with respect to the optical axis (20 ° light receiving angle) is attenuated by at least 25%, and at an angle of 20 ° or more. Incoming light (light receiving angle 40 °) is attenuated by at least 55%, and light arriving at an angle of 35 ° or more (70 ° light receiving angle) is attenuated by at least 85%.
[0065]
Accordingly, the step of performing an optical measurement attenuates light traveling at an angle of 10 ° or more with respect to the active display region by at least 25%, and light traveling at an angle of 20 ° or more with respect to the normal to the active display region. It has been found that the method can include selecting light for use in the control step by attenuating at least 55% and attenuating light traveling at an angle of 35 ° or more to the normal to the active display area by at least 85%.
[0066]
The area under the curve between the two angles gives a value for the amount of light received between these angles. One aspect of the present invention is to reduce the effect of light coming from an angle far from the normal to the display area (which can be distorted with respect to hue and / or brightness). Thus, according to another aspect of the invention, the ratio of the amount of light advanced and received at an angle of less than 15 ° to the normal to the display area and the amount of light advanced and received at an angle greater than 15 ° to the normal is , X: 1, where X is 1 or greater. Depending on the physical arrangement of the optical aperture and the length of the light guide, it is possible to eliminate light with a high exit angle.
[0067]
While the invention has been illustrated and described with reference to preferred embodiments, those skilled in the art will recognize that various changes and modifications in shape and detail may be made without departing from the scope and spirit of the invention. . For example, the dimensions of the optical sensor unit can be varied (larger or smaller optical sensor units) and thus the dimensions of the measurement zone can be larger or smaller. Also, the geometric arrangement of the optical sensor unit can be changed. Even if the optical sensor unit geometry and / or dimensions change, the optical sensor unit preferably protrudes above the active display area by a distance of less than 0.5 cm. Furthermore, the application can also be slightly different. For example, measuring the brightness for each color, either sequentially or by a combination of sensors with appropriate filters, measuring the color temperature defined by the mixture of primary colors, most often R, G and B, or Stabilize this. In another example, the method and apparatus are used to measure brightness measured with the described system and a second sensor directed to the room environment or the inactive edge of the display rather than the active area of the display. The contrast value with the ambient light can be stabilized. In this case, the display of the image on the active display area is controlled according to the optical measurement signal and the ambient light measurement signal combined therewith.
[Brief description of the drawings]
FIG. 1A is a top view of a part of an LCD screen with an optical sensor unit according to the present invention, and FIG. 1B is a part of an LCD screen with an optical sensor unit according to the present invention. FIG.
FIG. 2 shows a first embodiment of an optical sensor unit according to the present invention including a light guide assembled from different PMMA pieces.
FIG. 3 shows a second embodiment of an optical sensor unit according to the invention, including a light guide with an optical fiber.
FIG. 4 shows a third embodiment of an optical sensor unit according to the present invention including a light guide made of a single piece of PMMA.
FIG. 5 shows the light guide of FIG. 4 coated with a reflective coating.
6 shows the light guide of FIG. 4 partially coated with a reflective coating and shielded from ambient light by the housing.
FIG. 7 is a diagram showing a measurement mechanism for measuring the angular dependence of optical attenuation in a light guide.
FIG. 8 is a diagram illustrating how to measure the vertical angular dependence of optical attenuation in a light guide.
FIG. 9 is a diagram illustrating how to measure the angular dependence of the optical attenuation in the light guide in the horizontal direction.
10A is a diagram showing the results of the vertical angular dependence of optical attenuation at a light guide, measured as illustrated in FIGS. 7-9, and FIG. 7--shows the results of the horizontal angular dependence of optical attenuation at the light guide, measured as illustrated in FIG.

Claims (11)

A system for correcting light output and / or color of an image displayed on a display device (1) during display of a main application , said system comprising:
A display device (1) comprising an active display area (6) for displaying said image, an image forming device (2), and an electronic drive system (4) for driving said image forming device (2); ,
A light guide (34), an optical aperture (21) at one end of the light guide (34), a light sensor (22) at the other end of the light guide (34), and An optical sensor unit (10) for optically measuring the light output from a part of the active display area (6) and generating an optical measurement signal (11) therefrom , the light output of said part being Representing the light output of the active display area (6),
The system further includes:
A feedback system (12) for receiving the optical measurement signal (11) and controlling the electronic drive system (4) based thereon;
The light receiving angle of the light guide is such that light arriving at an angle of 10 ° or more with respect to the optical axis of the optical sensor is attenuated by 25% or more, light arriving at an angle of 20 ° or more is attenuated by 55% or more, and Light that arrives at an angle of 35 ° or more is attenuated by 85% or more,
The optical aperture (21) of the optical sensor unit (10) is disposed at a position for receiving light output from the front surface of a part of the active display area (6),
The photosensor (22) is located behind or on the side of the active display area (6),
The system for light output and / or color correction, wherein the portion of the active display area (6) is less than 1% of the area of the active display area (6) .   The system of claim 1, wherein the optical measurement is a luminance measurement.   The system of claim 2, wherein the light output correction includes brightness and / or contrast correction.   The system according to any of the preceding claims, wherein the light guide (34) is a light pipe.   The system of claim 4, wherein the light pipe is coated, thus shielding ambient light.   The system of claim 5, wherein the coating (36) does not penetrate into the material of the light pipe.   The system according to any of the preceding claims, wherein the light guide (34) is an optical fiber (32).   The system according to claim 1, wherein the optical sensor unit protrudes above the active display area by a distance of 5 mm or less. A method for correcting light output and / or color of an image displayed on a display device (1) during display for a main application , said method comprising:
Displaying the image on an active display area (6) on the display device (1);
For light emitted from a portion of the active display area (6), a light guide (34), an optical aperture (21) at one end of the light guide (34), and the light guide (34) ) using the other optical sensor at the end of (22) and an optical sensor unit comprising a (10) performs optical measurement, and a step of generating a future optical measurement signals (11), of the portion light The output represents the light output of the active display area (6),
The method further comprises:
Controlling the display of the image on the active display area (6) according to the optical measurement signal (11);
The light traveling at an angle of 10 ° or more with respect to the active display area is attenuated by 25% or more, and the light traveling at an angle with the normal to the active display area of 20 ° or more is attenuated by 55% or more. Attenuating 85% or more of the light traveling at an angle of 35 ° or more with respect to the normal to the display area,
The optical aperture (21) of the optical sensor unit (10) is disposed at a position to receive light output from the front surface of the portion of the active display area (6),
The light sensor (22) is arranged behind or on the side of the active display area (6);
Method for light output and / or color correction, wherein the portion of the active display area (6) is less than 1% of the area of the active display area (6) of the imaging device (2) .   The method of claim 9 for performing a luminance measurement.   The method of claim 10, wherein the light output correction includes brightness and / or contrast correction.

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